In the production process of PCB, in order to be able to interconnect the upper and lower levels, drill pin is needed to penetrate the insulating layer in a small area before electroplating the conductive layer. During the drilling process, in order to improve the drilling accuracy and reduce the drilling burrs, an aluminum cover plate is placed over the copper clad laminate (CCL) to be drilled and a back up board is placed under the CCL, in order to help in heat transfers, guidance and protections to the drilling pin. In the present technologies, the lubricating and radiating resin is mainly applied to the cover plate; however, after the drill passes through the cover plate and the PCB plate, the lubrication and radiation capacities of the resin have been almost totally consumed. After the drilling process, the PCB generates relatively large heat and which is easy to make the copper surfaces red and even get separated. Therefore, the prior art needs to be improved and developed.